A bucket toilet is a 20 L food-grade plastic bucket with a 5 cm sawdust base, set under a seat on a plywood box and emptied into an outdoor compost bin when it is about 3/4 full, which is 15 L. With the cover and faeces volumes worked out below, that is every 4 to 6 days for a family of four if urine is diverted, and about every 2 days if it is not.
Part of Composting Toilet Systems
The bucket system is the simplest waterless toilet: a removable container under a seat, covered with dry carbon after each use and tipped into a separate compost bin. It needs no excavation and can be built in an afternoon.
The Bucket Is Cheap; The Emptying Routine Is The System
Everything that makes this toilet safe happens at the cover step and the emptying step. The parent page calls it proven by decades of use, provided every deposit is completely covered and no waste is ever left visible. Smell is the alarm: if it smells, there is not enough cover.
What You Need
- A 20 L bucket with a lid — food-grade plastic is chemically stable; once used for waste it is never again used for food or water
- A plywood box with a seat sized to hold the bucket snugly and a lid on the seat
- Cover material in quantity — sawdust is ideal (Sawdust, Straw & Leaf Mold)
- A second bucket — one stays in service while the other is emptied, rinsed and dried
- An outdoor bin that receives only humanure, with straw, leaves or sawdust beside it (Compost Bin Construction)
- A hand-washing station within reach of the door
Method: Use, Cover, Empty, Rinse
Step 1: Prepare the bucket. Put 5 cm of sawdust in the bottom. It absorbs the first moisture and starts the carbon bed.
Step 2: Cover after every use. Pour sawdust over the deposit until none shows. When it is right there is almost no odour; when it is going wrong you smell it and see flies.
Step 3: Empty at about 3/4 full. Do not wait until the bucket is brimming. Put on gloves, lid the bucket, carry it directly to the bin and keep it level.
Step 4: Tip into the centre of the bin. Do not scatter; a concentrated mass holds heat. Cover at once with a thick layer, 10-15 cm, of straw, leaves or more sawdust.
Step 5: Rinse sparingly. Rinse the bucket with a little water and pour the rinse into the bin, never down a drain or onto the ground.
Step 6: Dry, re-line and return. Add fresh sawdust to the clean bucket and put it back in service.
Worked Example: How Often Does A Bucket Fill?
Inputs, with sources:
- Working volume = 3/4 of 20 L = 15 L.
- Cover: Composting Toilet gives about 500-750 mL per person per day.
- Faeces: about 0.13-0.25 L per person per day (recalled from published measurements of wet faeces, roughly 130-250 g per person per day at about 1 kg per litre; not re-read).
- Urine, if not diverted: about 1.4 L per person per day (also recalled).
- People: four (4).
Urine diverted. Solids plus cover per person = 0.63-1.0 L/day. For 4 people = 2.5-4.0 L/day. Days to fill 15 L = 15 ÷ 4.0 to 15 ÷ 2.5 = 3.8 to 6.0 days.
Urine not diverted. Per person = 2.05-2.42 L/day, so for 4 people = 8.2-9.7 L/day. Days to fill = 15 ÷ 9.7 to 15 ÷ 8.2 = 1.5 to 1.8 days.
That is why a bucket without diversion is a daily chore and a wet, smelly one. The extra liquid is also what turns the contents anaerobic.
A full 15 L bucket weighs about 15 kg if its contents are close to 1 kg per litre. Lift with a straight back, or empty at half full if the carrier is small or frail.
Common Mistakes
- Leaving the bucket to fill to the brim. It spills on the walk and cannot be covered.
- Too little cover. The parent page names this the number one cause of smell and flies.
- Pouring rinse water anywhere but the bin. It is dilute human waste.
- Siting the bin near a well, spring or stream. Source Protection lists compost heaps within 30 m of a source as a high risk. That distance assumes soil filters the seepage; in fissured rock or karst distance alone is not protection.
- Using the same bucket for washing or food afterwards.
Safety
Spills and splashes carry the full range of faecal pathogens
Wear gloves and closed shoes when emptying, lid the bucket for carrying, and wash hands with soap or ash and water immediately afterwards. Keep children from the bin. If a bucket spills, cover the spill with dry sawdust, scoop into the bin, and wash the ground area with soapy water directed into the bin, not into a drain.
What’s Next
- Learn next: Compost Bin Construction — where the bucket goes
- Combine with: Urine-Diverting Systems — stretches the interval between emptyings from 1.5-1.8 days to 3.8-6.0 days in the example above